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Number of pregnancies linked to AF risk
Findings from a follow-up analysis in the Women’s Health Study show that multiple pregnancies may be related to subsequent atrial fibrillation risk in initially healthy women.
Jorge A. Wong, MD, MPH, from the Population Health Research Institute at McMaster University in Hamilton, Ontario, Canada, and colleagues examined the relationship between parity and AF in women from the Women’s Health Study, a large prospective cohort study. All the women were free of CVD and AF at baseline.
“We found that an increase in the number of pregnancies was associated with a higher risk of future [AF],” Wong said in a press release. “For example, women with four or more pregnancies were approximately 30% to 50% more likely to develop [AF] compared to women with no pregnancies.”
Participants from the Women’s Health Study, which was completed in 2004, were invited to take part in observational follow-up. The women self-reported the number of pregnancies they had that lasted at least 6 months. They also reported incident AF beginning at 48 months and annually thereafter; however, only incident AF events that could be confirmed by medical record review were included in the evaluation.
The median age of the women included in this follow-up (n= 34,639) was 53 years, with a median number of pregnancies of two. Median follow-up time was 20.5 years. During this time, 1,532 incident AF cases occurred.
A linear increase was found in the HR for incident AF after adjusting for age. This was found as the number of pregnancies went up (P for trend = .004).
After controlling for BMI, diabetes, other AF and CVD risk factors, reproductive factors and markers of socioeconomic status, the relationship between incident AF and parity was even stronger (P for trend < .0001), the researchers wrote.
“Repeated exposure to metabolic, physiological and hormonal changes during pregnancy may predispose to AF in later life and requires further investigation,” Wong and colleagues wrote.
The results also did not differ after adjusting for interim CVD events.
“Our study is the first to report an independent association between parity and AF risk. In comparison with nulliparous women, increasing number of pregnancies was associated with a linear increase in the risk of incident AF after adjustment for multiple confounders including shared risk factors such as obesity, hypertension, and diabetes mellitus, and reproductive risk factors and socioeconomic markers, as well,” Wong and colleagues wrote.
“The point here is not to discourage women from having children,” Wong said in the release. “However, our research highlights that something about pregnancy predisposes women to this greater risk, and more research is needed to help us understand why.” – by Suzanne Reist
Disclosure: The researchers report no relevant financial disclosures.